Congenital non-syndromal sensorineural hearing impairment due to connexin 26 gene mutations - molecular and audiological findings

We screened DNA from 72 sibships and 138 sporadically affected individuals with congenital non-syndromal sensorineural hearing impairment (NSSNHI) for mutations in the 26 (CX26) gene. A total of 20 (27.8%) of the sibships and 11 (7.9%) of the sporadically affected individuals were homozygous or comp ound heterozygotes for CX26 mutations. A total of 11 (17.2%) of 64 individu als with severe and 30 (30%) of 100 with profound NSSNHI compared to eight (8.7%) of 92 persons with moderate and none (0%) of 19 individuals with mil d hearing impairment were homozygous or compound heterozygotes for CX26 mut ations (chi(2) test, 3 df, P = 0.000). CX26 mutation status had no effect o n the symmetry of the hearing impairment or configuration of the audiogram. In addition, serial audiograms showed no evidence of progression of the he aring impairment or differences in the severity of the hearing impairment i n affected siblings in persons whether or not due to CX26 mutations. Sporad ically affected individuals with congenital NSSNHI should be routinely test ed for mutations in CX26, especially if the hearing impairment is severe or profound in severity, since identification of a mutation in CX26 allows us e of Mendelian recurrence risks. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.